1. Field of the Invention
The present invention relates to containers, and more particularly, to a closure for a container which provides visual indication to a consumer when the lid has been previously removed.
2. Description of the Prior Art
A large number to tamper proof and tamper evident containers have been proposed in the prior art. One of the most successful methods is to provide a lid which requires the removal of a portion thereof along a "tear-strip" line since, after opening, the torn part cannot be reasonably reassociated with the lid and the evidence of tampering is manifest. Such lids, however, require that there be no reasonable alternate way of removing the lid without tearing the strip and, a number of solution to this problem have also been proposed. One such arrangement is to provide an inwardly extending locking piece attached to the tear strip and arranged at an angle upwardly so as to catch an outwardly extending portion of the cup shaped container. Such an apparatus is seen in patents such as the Krout U.S. Pat. No. 4,476,993 issued Oct. 16, 1984, the Smith U.S. Pat. No. 4,493,432 issued Jan. 15, 1995, the Bordner U.S. Pat. No. 4,718,571 issued Jan. 12, 1988, the Chumley et al. U.S. Pat. No. 4,881,656 issued Nov. 21, 1989 and the Smith U.S. Pat. No. 5,002,198 issued Mar. 26, 1991. The locking arrangements of such patents can be successful in making the lid of the container difficult to remove without obviously harming the lid itself or without tearing the tear-strip as long as the lock is properly applied. Some of these structures apply the locking device in only a few places spaced around the periphery of the container which may permit bending of the device out of the way of the outwardly extending portion of the container. A better arrangement is to have a completely locking ring extending around the entire periphery as in the Smith U.S. Pat. No. 5,002,198 mentioned above. However, a difficulty is encountered in the Smith arrangement because the upwardly extending conical locking ring is formed as an integral part of the downwardly extending tear strip and, when the lid is inserted over the rim of the container, the ring is supposed to be moved aside to permit the rim of the container to move past the locking ring and spring back to a position under the outwardly extending portion so that any attempted upward movement of the lid thereafter will cause the locking rim to engage the lip of the container and prevent opening. Unfortunately, the forcing of the lid over the upwardly extending conical locking ring may not, in all cases, provide assurance that the conical locking ring has in fact moved back into engagement with the lip of the container. More particularly, if the container lid is not pressed all the way down a portion or the locking ring may be wedged against the lip of the container which would then allow a careful removal of the lid without tearing the strip or damaging the lid or container. It is desirable to have a more positive locking arrangement without loosing the inherent desirability of the conical locking ring arrangement.